I quite often use aluminum in projects where the look of it is important. Today, I edged a board for a sliding shelf with aluminum channel. To make it look better, I sanded the pieces. Got rid of the scratches, but there are these annoying 'spots' showing up on the freshly sanded surface. Thinking I was getting fingerprints on it, I carefully cleaned, then went at it again. I can't seem to be able to sand the 'marks' away, they just sort of pop into existence during sanding. They look like fingerprints, about that size. I've tried water and oil with the sandpaper, of which I have tried at least 3 different types. I can't get a consistent surface. I've done this before, sanding al, and sometimes, but not always, this problem comes up. Does anyone know what is happening here?
I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-